“Diameter” is an authentication, authorization, and accounting protocol (“AAA”) for computer networks. The Diameter base protocol is defined by RFC 6733 and defines the minimum requirements for an AAA. The Diameter base protocol is intended to provide an AAA framework for applications such as network access or Internet Protocol (“IP”) mobility in both local and roaming situations.
Diameter applications can extend the base protocol by adding new commands, attributes, or both. A Diameter application is not a software application but is a protocol based on the Diameter base protocol. Each application is defined by an application identifier and can add new command codes and/or new mandatory attribute-value pairs (“AVP”s). Examples of Diameter applications include various applications in the 3rd Generation Partnership Project (“3GPP”) mobile telecommunication standards.
One example of a Diameter application, the 3GPP “Gx” application, which is used between the Policy and Charging Rule Function (“PCRF”) and the Policy and Charging Enforcement Function (“PCEF”), is based on the Diameter standard and is primarily used to perform monitoring, authorization, Quality of service (“QoS”) and charging control of users' traffic (e.g., Long Term Evolution (“LTE”) traffic) in accordance with the operator's policies.
Another example of a Diameter application is the “Rx” application, which is used between the Application Function (“AF”) and the Policy and Charging Rule Function (“PCRF”). It is used to monitor, authorize and control application related traffic (e.g., IP Multimedia Subsystem (“IMS”) related traffic of users). The AF interacts with the PCRF over Rx by providing service related information. The PCRF, upon receipt of service information from the AF over Rx, provisions corresponding policy and charging rules on the PCEF via Gx to control the data flows signaled over Rx.